With the rising popularity of cloud computing, remote desktop environments, such as those based on Virtual Desktop Infrastructure (VDI) and Desktop-as-a-Service (DAAS) have become rapidly growing industries. In a conventional VDI or DAAS environment, a user is provisioned a virtual desktop and is allowed to access their virtual desktop over a remote network connection, such as a WAN connection. The virtual desktops are typically hosted on servers that reside in a data center of the enterprise (or a third party service provider), and each host server may execute multiple virtual desktops. Users can utilize a client device to remotely log into their individual virtual desktop and all of the application execution takes place on the remote host server which is linked to the local client device over network, using a remote display protocol such as remote desktop protocol (RDP), PC-over-IP (PCoIP) protocol, virtual network computing (VNC) protocol, or the like. Using such a remote desktop protocol, the user can interact with applications of the virtual desktop, which are running on the remote host server, such that only the display, keyboard, and mouse information is communicated with the local client device. A common implementation of this approach is to host multiple desktop operating system instances on a server hardware platform running a hypervisor.
In many ways, VDI and DAAS provide a more centralized and efficient computing environment because each user is able to access their individual desktop from any device capable of making a network connection and from virtually any location. All of the user data is stored in the cloud (e.g., in a remote data center), providing more centralized management and quality of control for the organization that may employ the individual users.
End-user experience plays a key role for the seamless transition from traditional workstations to virtual desktops, such as VDI and DAAS. Remote display protocols provide the display of the virtual desktops or applications to the end-user and it is essential for the protocol to provide the same look (visual perception) and feel (responsiveness) as physical workstations. While the responsiveness metric has been studied in great details from the evolution of VDI, there has been less focus and exploration on the visual perception because of its subjective evaluation. However, understanding visual perception quality objectively is important when deploying a virtual desktop solution so that appropriate amount (and type) of resources can be allocated and utilized. For example, both responsiveness metrics and visual perception measurements can be useful to benchmark different CPU architectures, hosts, storage architectures and to study the impact of different configurations and optimizations that can be done at different layers of hardware and software stack of a VDI or DAAS deployment. Often, slight changes in image quality can significantly change the underlying bandwidth usage (e.g., in some cases, up to 30% or more). For example, PCoIP is a display protocol implemented in VDI which first provides an initial image of lower quality and then builds to lossless quality (100% quality). In the case of VDI, perceptually lossless quality of 90% can usually provide the same look and feel of VDI desktops to the end user and hence there is no need to build to fully lossless quality except in certain circumstances. This can provide substantial bandwidth savings (e.g., up to 20%) and can therefore reduce the required allocation of resources needed to deploy a VDI solution. As such, there is a need to understand visual perception objectively and to include it in a comprehensive user experience analysis.